An in-vehicle emergency report device executes an emergency operation for transmitting an emergency report signal to a service center when the vehicle collides with an obstacle or a human, or when a user depresses an emergency report button. This device is powered with a battery: The battery voltage may decrease e.g., when an airbag expands. When the battery voltage decreases less than a given level, the device stops the emergency report operation, posing a problem. To solve this problem, a dedicated accessory battery other than the above battery is mounted (refer to Patent Document 1).                Patent Document 1: JP-2000-322677 A        
This accessory battery allows the emergency report device to complete transmitting the emergency report signal to the center without stopping the operation; however, mounting the accessory battery involves an additional cost or an additional space for mounting, posing a problem.